Passive Optical Network Upstream Burst Pairing
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Solution Overview
Problem
Current PON technologies face challenges in achieving high upstream throughput and low latency while maintaining low-cost optical transceivers, particularly at the customer side, leading to potential bottlenecks in future networks.
Innovation Solution
A device and method that dynamically pair optical network units (ONUs) based on optical power levels, extinction ratios, and transmission wavelengths to allow simultaneous burst transmission within time intervals, optimizing upstream throughput and latency by generating new modulation formats and adapting bandwidth allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional TDMA protocol is used with fixed time intervals for upstream transmission, then collision avoidance is achieved, but upstream throughput is limited and latency increases
Solution Approach 1:
The patent applies dynamic bandwidth allocation where the OLT adjusts the length of time intervals assigned to different ONUs based on their service demands. High-latency-sensitive services receive shorter time intervals while bulk data services receive longer intervals, making the time allocation adaptive rather than fixed. This dynamic adjustment allows the system to optimize throughput and latency in real-time based on actual traffic conditions.
Solution Approach 2:
The patent segments the upstream transmission timeframe into multiple variable-length time intervals, each assigned to different ONUs or groups of ONUs. Instead of a single fixed time slot for all ONUs, the timeframe is divided into multiple segments that can be allocated flexibly. This segmentation enables parallel transmission from multiple ONUs without collisions while optimizing the total throughput by allowing simultaneous transmissions from different users.
2Productivity
If optical transceivers at ONU side are made high-cost to support high upstream capacity, then upstream throughput increases, but device cost increases
Solution Approach 1:
The patent merges multiple ONUs into groups that transmit simultaneously using wavelength division multiplexing. Instead of requiring each ONU to have high-cost transceivers for high throughput, the system combines multiple lower-cost ONU transmissions into a single aggregated upstream channel. The OLT receives combined optical signals from multiple ONUs and separates them using wavelength filtering, achieving high aggregate throughput without requiring expensive transceivers at each ONU.
Solution Approach 2:
The patent introduces the OLT as an intermediary that performs wavelength division multiplexing and demultiplexing. The OLT acts as a mediator that combines signals from multiple ONUs with different wavelengths into a single optical channel for transmission through the passive optical network. This intermediary approach allows multiple ONUs to share the upstream channel efficiently without requiring each ONU to have high-cost transceivers, as the wavelength separation and combining is performed at the OLT.
3Loss of time
If time intervals are allocated dynamically based on service demands, then latency for high-priority services decreases, but control complexity increases
Solution Approach 1:
The patent applies local quality by assigning different time interval characteristics to different ONUs based on their specific service demands. Each ONU or service class receives customized time allocation parameters - high-priority services get shorter intervals with lower latency while bulk services get longer intervals. The DBA controller implements this by making localized adjustments to individual time slot assignments rather than applying a uniform approach, allowing optimization for specific service requirements without requiring complete system redesign.
Data Source
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Figure 5A~6C
AI summary
A device for controlling upstream transmission of bursts from ONUs (131-13n; A-G) to an OLT (111) in a PON, wherein the upstream transmission is organized in time intervals (401-407) that form part of an upstream timeframe (400), comprises: - means (303) to obtain respective optical power levels received at the OLT (111) for the ONUs (131-13n; A-G); - means (303) to obtain respective extinction ratios at the OLT (111) for the ONUs (131-13n; A-G); - means (303) to obtain respective transmission wavelengths for the ONUs (131-13n; A-G); - means (305, 306) to distinguish pairable ONUs (B, C, D, F, G) and non-pairable ONUs (A, E) at least based on the wavelengths; - means (301; 305) for pairing the pairable ONUs based on the optical power levels and/or the extinction ratios, thereby generating one or plural subsets of paired ONUs (D, F; B, C, G); - means (306, 307) for allowing paired ONUs (D, F; B, C, G) that belong to a same subset to simultaneously transmit bursts within a time interval (406; 407).